Heat exchanger

ABSTRACT

A heat exchange device comprising at least one heat exchange surface ( 2 ), wherein the heat exchange surface comprises one or more parallel tubular lines ( 3 ), a rapper device and an impact area for the rapper device. The impact area comprises an impact block ( 6 ) with one or more inner channels ( 7 ) through which coolant flows bridging opposite open ends ( 5 ) of an interrupted tubular line of the heat exchange surface. The impact block ( 6 ) enforces the impact area of the heat exchange surface and translates impact energy caused by a rapper device very effectively into mechanical waves through the heating surface, resulting in an improved cleaning effect.

The present invention relates to a heat exchange device with at least one heat exchange surface comprising one or more parallel tubular lines and an impact area for a rapper device for cleaning the heat exchange surface.

Such heat exchange devices are for example used in gasification processes for the production of synthetic gas, also called syngas. In such a process, carbonaceous feedstock is partially oxidised in a reactor. Syngas leaving the reactor typically has a temperature of 1300-1400° C. The hot syngas is transported to a heat exchanger, generally comprising a number of rigidly connected, parallel helically coiled tubes.

U.S. Pat. No. 5,482,110 discloses a heat exchanger for cooling syngas from a partial combustion reactor. The heat exchanger comprises nested heat exchange surfaces. Particularly for the cooling of deposit-forming gases from pressure-loaded pyrolysis and gasification reactors it is desirable that the heat exchange surfaces are cleaned to maintain maximum heat dissipation. The heat exchange surface can be cleaned using rapping devices, or rappers, which can regularly be actuated during operation of the reactor. An example of such a rapper device is disclosed in British patent application GB 2 104 614 A. When the rapper device impacts the heat exchange surface, the surface is accelerated to such an extent, that soot deposits and fouling are effectively removed. Cleaning by rapping can be particularly effective if all tubes of one heat exchange surface are rigidly connected to form one constructive gastight unit, e.g., by constructing the heat exchange surfaces as a tube-stay-tube or fin-tube construction. The impact of the rapper device causes high peak loads on the heat exchange surface, which can cause damage of the tubes and leakage of coolant.

It is an object of the present invention to provide a heat exchanger device which has an improved resistance against impact loads by rapper devices, and which enables more effective cleaning by rapping.

The object of the invention is achieved by a heat exchange device comprising at least one heat exchange surface, wherein the heat exchange surface comprises one or more parallel tubular lines and an impact area for a rapper device, the impact area comprising an impact block with one or more inner channels, each inner channel bridging opposite open ends of an interrupted tubular line of the heat exchange surface. The impact block is integrated into the surface of the heat exchanger so that the impact block is in direct contact with the hot syngas.

Because the impact block is integrated into the heat exchanger surface, the impact block translates the impact energy caused by a rapper device very effectively into mechanical waves through the heating surface. The impact block can be made very rigid and stiff to improve the transfer of impact loads by the rapper. As a result, a very good cleaning effect can be obtained. If the force from the rapper device is not effectively transferred, then little or no cleaning is accomplished. The impact block enforces the impact area of the heating surfaces, so the lifetime of the heat exchange surface can be substantially increased. The inner channels can be made with the same diameter as the flow paths in the tubular lines so that the flow paths are continued via the inner channels in the impact block without substantial obstructions. This design allows for effective cooling of the impact block by allowing coolant to flow unimpeded through the impact block.

The heat exchange surface can for example be a cylindrical heat exchange surfaces, e.g., built of a plurality of straight or coiled tubular lines for transporting a fluid heat exchange medium, such as cooling water. Alternatively, the heat exchange surface can be a flat surface built of a plurality of straight tubular lines.

In a particular embodiment, the tubular lines are coiled and one or more of the tubular lines are interrupted at the impact area, wherein an impact block with a flat outer surface is provided with one or more inner channels, each channel operatively connecting the opposite ends of one of the interrupted channels. The inner channels in the impact block can be straight channels and have a straight longitudinal axis.

To provide a reliable connection between curved tubular lines and a rectangular impact block with flat surfaces, transitional wedged tube sections can be used. The contact faces between the transitional wedged tube sections and the impact block can be made perpendicular to the flat outer surface of the impact block. The transitional wedged tube section can for example be welded to the impact block, which gives a reliable and durable joint. Also the ends of the interrupted tubular line at the impact area can be perpendicular to the longitudinal axis of the tubular lines. The ends of the interrupted tubular lines, the ends of the inner channels in the impact block and the transitional wedge sections can be provided with circular rims on which the welding seam can be applied.

The impact block may for example embed two, three or four inner channels, or more, if so desired.

The impact block may for instance carry an anvil. The rapper device can impact the anvil, which transfers the impact load via the impact block to the heat exchange surface. The anvil can for example be a hollow cylinder having one side welded to the flat outer surface of the impact block and another side capped with a solid block.

The heat exchange device can comprise one or more heat exchange surfaces formed by two or more coiled tubes, wherein at the ends of the heat exchange surfaces each of the coiled tubes branches off from the corresponding heat exchange surface and bends away from an adjacent coiled tube, and wherein a reinforcement web extends between the bent part and the adjacent tube.

The heat exchange surfaces can for example be assembled as a plurality of coaxially nested heat exchange surfaces of a closed geometry, such as a cylindrical geometry, whereby the inner heat exchange surface extends beyond the adjacent outer heat exchange surface so that each heat exchange surface can be rapped from the exterior without the need for penetrating any other heat exchange surface.

Alternatively, the heat exchange device may comprise straight tubular lines forming one or more flat heat exchange surfaces. In such a case, the impact block can be positioned at one of the sides of the heat exchange surface. Optionally, the impact block carries an anvil plate at its lateral side forming an impact area under right angles with the heat exchange surface. This way, the rapper can impact the heat exchange surface from a lateral direction, resulting in a very effective transfer of mechanical energy.

The invention is further explained under reference to the accompanying drawings. In the drawings:

FIG. 1: shows a part of a heat exchange surface with an impact block of a heat exchange device according to the present invention;

FIG. 2: shows a side view of the section of FIG. 1;

FIG. 3A: shows in plan view an impact block of the heat exchange surface of FIG. 1;

FIG. 3B: shows the block of FIG. 3A in side view;

FIG. 4A: shows in front view a part of a heat exchange surface with an impact block of an alternative embodiment of a heat exchange device according to the present invention;

FIG. 4B: shows the section of FIG. 4A in plan view;

FIG. 5A: shows in front view a part of a heat exchange surface with an impact block of a further alternative embodiment of a heat exchange device according to the present invention;

FIG. 5B: shows the section of FIG. 5A in plan view.

FIG. 1 shows an impact area 1 of a heat exchange device according to the present invention. The heat exchange device comprises one or more cylindrical heat exchange surfaces 2 formed by a number of coiled parallel tubular lines 3. The tubular lines 3 are welded together via fins 4 to form a gastight cylindrical wall.

Three of the tubular lines 3 are interrupted at the impact area 1. Each of the interrupted lines 3 has two opposite ends 5 at the impact area 1 (see FIG. 2). These ends 5 are connected by an impact block 6 having three straight parallel channels 7 (see FIG. 3A) crossing the block 6 from one side 8 to an opposite side 9. The impact block 6 is shown as a separate part in FIG. 3A. The open ends of the channels 7 are surrounded by circular rims 10 to enable leak tight welding joints.

Each channel 7 is in line with one of the interrupted tubular lines 3 and in open connection with one of the opposite ends 5 of the corresponding interrupted tubular line 3, so that coolant flows through each channel 7. The channels 7 have the same cross sectional area as the tubular lines 3. The block 6 has a flat outer surface 8. The block 6 is connected to the ends 5 of the interrupted coiled tubes 3 via transitional wedged tube sections 11. The transitional wedged tube sections 11 are tubular and have two ends 12, 13 under an angle with each other—the first end 12 being configured to engage the end 5 of an interrupted coiled line 3, while the other end 13 is configured to engage the circular rim 10 of one of the channels 7 in the impact block 6. The ends 12, 13 of the transitional wedged tube sections 11 are also provided with circular rims 14 to enable leak tight welding seams.

The ends of the channels 7 in the impact block 6 and the ends of the coiled tubular lines 3 at the impact area 1 are under right angles with the corresponding longitudinal axes A, A′. This way, the impact block 6 and the transitional wedged tube sections 11, and the connection between the ends 5 of the interrupted coiled tubes and the transitional wedged tube sections 11 can be welded to form a very reliable and durable high quality joint.

The flat upper surface 8 of the impact block 6 carries an anvil 15. A rapper device (not shown) is arranged to impact the anvil 15, which transfers the impacted load to the heat exchange surface. Since the anvil 15 stands under right angles with the flat upper surface 8 it can be joined to the flat surface 8 of the impact block 6 by a durable weld. The anvil 15 is formed by a hollow cylinder 16 capped with solid block 17.

In FIG. 1 the impact area 1 is located near the lower end of the heat exchange device. At this lower end of the heat exchange surface the coiled tubes 3 have a bent section 18 branching off from the heat exchange surface. The bent section 18 bends away from an adjacent coiled tube 3. A reinforcement web 19 extends between the bent section 18 and the adjacent tube 3.

FIG. 4A shows an impact area 21 of an alternative embodiment of the heat exchange device according to the present invention. The heat exchange device comprises a cylindrical heat exchange surface 22 formed by a number of straight, vertically arranged parallel tubular pipe lines 23. As in the embodiment of FIG. 1, the tubular pipe lines 23 are welded together via fins 24.

Three of the tubular lines 23 are interrupted at the impact area 21. Each of the interrupted lines 23 has two opposite ends 25 at the impact area 21. These ends 25 are connected by an impact block 26 having three straight parallel channels 27 (see FIG. 4B) crossing the block 26 from one end 25 to an opposite end 25 of an interrupted tubular line 23. The open ends 25 of the channels 27 are surrounded by circular rims 30 to enable leak tight welding joints. Each channel 27 is in line with one of the interrupted tubular lines 23 and in open connection with one of the opposite ends 25 of the corresponding interrupted tubular line 23. The channels 27 have the same cross sectional area as the tubular lines 23.

The block 26 has a flat outer surface 28 which carries an anvil plate 35. A rapper device (not shown) is arranged to impact the anvil plate 35 in the direction indicated with arrow B (see FIG. 4B).

FIG. 5A shows an impact area 41 of a further possible embodiment of the heat exchange device according to the present invention. This embodiment comprises a flat heat exchange surface 42 formed by a number of straight, vertically arranged parallel tubular pipe lines 43. As in the embodiments described above, the tubular pipe lines 43 are welded together via fins 44. The heat exchange device may comprise one or more of such flat heat exchange surfaces, e.g., in a parallel arrangement.

At the right side of the heat exchange surface, three adjacent tubular lines 43 are interrupted at the impact area 41. Each of the interrupted lines 43 has two opposite ends 45 at the impact area 41. These ends 45 are connected by an impact block 46 having three straight parallel channels 47 (see FIG. 5B) crossing the block 46 in a direction in line with the tubular lines 43. The open ends of the channels 47 are surrounded by circular rims 50 to enable leak tight welding joints. Each channel 47 is in line with one of the interrupted tubular lines 43 and in open connection with one of the opposite ends 45 of the corresponding interrupted tubular line 43. The channels 47 have the same cross sectional area as the tubular lines 43.

The block 46 has a flat lateral side 51, which carries an anvil plate 55 perpendicular to the heat exchange surface. A rapper device (not shown) is arranged to impact the anvil plate 55 in a direction indicated by arrow C parallel to the heat exchange surface. 

1. A heat exchange device comprising at least one heat exchange surface, wherein the heat exchange surface comprises one or more parallel tubular lines and a rapper device and an impact area for the rapper device, the impact area comprising an impact block with one or more inner channels through which coolant flows, each inner channel bridging opposite open ends of an interrupted tubular line of the heat exchange surface.
 2. A heat exchange device according to claim 1 wherein the tubular lines are coiled.
 3. A heat exchange device according to claim 2 wherein transitional wedged tube sections each connect an inner channel in the impact block to the corresponding end of an interrupted coiled tube.
 4. A heat exchange device according to claim 3, wherein the contact faces between the transitional wedged tube sections and the impact block are perpendicular to the flat outer surface of the impact block.
 5. A heat exchange device according to claim 1 wherein the impact block embeds two, three or four inner channels.
 6. A heat exchange device according to claim 1 wherein the impact block carries an anvil.
 7. A heat exchange device according to claim 1 wherein at the ends of the heat exchange surfaces each of the coiled tubes branches off from the corresponding heat exchange surface and bends away from an adjacent coiled tube, and wherein a reinforcement web extends between the bent part and the adjacent coiled tube.
 8. A heat exchange device according to claim 1 wherein the heat exchange device comprises straight tubular lines forming a flat heat exchange surface.
 9. A heat exchange device according to claim 8 wherein the impact block is positioned at one of the sides of the heat exchange surface.
 10. A heat exchange device according to claim 9 wherein the impact block carries an anvil plate at its lateral side forming an impact area under right angles with the heat exchange surface. 